在python类之间传递参数

Question

I'm attempting to write my first python module. The module is a wrapper for an api.

I'd like to allow users to set an api key in one of two ways: using a static configuration file or dynamically when they initiate the class.

How do I pass the key from __init__.py to functions.py if the key is in fact set dynamically?

File structure:

package/
   __init__.py
   config.py
   functions.py

File contents:

__init__.py

import config 

class MyClass(object):
    def __init__(self, key):
        self.key = key if key else config.key
        ...

functions.py

import config 

class MyFunctions(object):
    def __init__(self):
        self.key = ?
        self.base_url = config.base

    def function1(self, my_id):
        endpoint = urlencode({'id':my_id, 'key':self.key})
        ...

config.py

key = 'xxxxxxxxxxx'
base= 'http://xxxxx.com/api'

Answer 1

Assuming you want to set the same key for all the classes in the functions module, do so in the initialization of the package, overwriting the variables set by default in the config module.

Then import the config module and use the variables

config.py

key = 1
base_url = 'www.xyz.com/'

__init__.py

import config
import functions

class MyClass(object):
    def __init__(self, key=config.key):
        config.key = key

functions.py

import config 

class MyFunctionsA(object):
    def function1(self, my_id):
        print(config.base_url)
        print(config.key)

class MyFunctionsB(object):
    def function1(self, my_id):
        print(config.base_url)
        print(config.key)

class MyFunctionsC(object):
    def function1(self, my_id):
        print(config.base_url)
        print(config.key)

So you can use them as

>>> import package as pk
>>> pk.MyClass(9)
<package.MyClass object at 0x7f2133e96d10>
>>> f1 = pk.functions.MyFunctionsA()
>>> f2 = pk.functions.MyFunctionsB()
>>> f3 = pk.functions.MyFunctionsC()
>>> f1.function1(100)
www.xyz.com/
9
>>> f2.function1(100)
www.xyz.com/
9
>>> f3.function1(100)
www.xyz.com/
9

However, in case the key is an instance attribute of MyFunctions , let the users pass the key to its __init__ , as usual.

Note: I ignore why you need to instantiate MyClass to set things up. It may be simpler to use a plain function instead.